Black Blade is not the first exercise organised by the European Defence Agency.

Dozens of drills have taken place in just the last year in an effort to “enhance and sustain some key European defence capabilities”.

Defence research spending by EU governments has fallen by a third since 2006, leaving the EU reliant on the United States for advanced war-fighting equipment.

During the US election campaign, Donald Trump questioned whether America should protect allies seen as spending too little on their defence, raising fears that he could weaken support for NATO at a time of heightened tensions with Russia.